The Homogenizing Effects of Dielectric Functionally Graded Material on the Cylindrical Spacers with Insulating Defects

This paper provides an exploration about how dielectric functionally graded material (d-FGM) homogenize electric field on the cylindrical spacers with some general defects. The simulation models of cylindrical spacers with 3 kinds of defects, internal pore, surface pore and surface metal particle are simulated by COMSOL. Furthermore, the corresponding real models are prepared by thermal curing and their partial discharge properties are tested under 50Hz AC voltage. The results indicate that d-FGM has a good effect on homogenizing electric field in these 3 cases. The maximum electric field strength is reduced by about 62^% and 53 % for internal pore and surface pore defects, respectively. For the surface metal defect, the area of electric field concentration is significantly reduced. The partial discharge inception voltages (PDIV) are increased by about 19.0% and 31.1 % for internal pore and surface pore defects, respectively. While for surface metal particles, the PDIV is increased by 3.6%. This research verifies that even though the insulating defects exist, the d-FGM still have good effect in homogenizing the electric field distribution.